In general, resin materials (plastics) are widely used to provide lighter and smaller designs for various electrical and electronic devices. For example, the structure of an embedded antenna in a mobile phone may include a pattern (loop) for wireless transmissions and receptions formed on a surface of a body molded with a PC (polycarbonate) material, for its exceptional qualities in terms of impact resistance and wear resistance.
In the past, it was common to utilize the method of thermally fusing a metal piece forming a particular pattern onto a resin body. However, this method may result in defects, such as the metal piece becoming partially separated from the resin body due to uneven adhesion across the pattern, and there may also be difficulties in maintaining important properties, such as for wireless communication or electromagnetic shielding, for extended periods of time. Because of these reasons, a preferred method for forming a conductive pattern on a non-conductive body is electroless plating, as it entails relatively less property changes. Electroless plating involves applying a reducing agent to a solution containing metal ions in order to reduce and deposit the metal onto an object, and is differentiated from immersion plating in ionization tendency.
One example is found in Korean Patent Publication No. 10-2005-0122000, which discloses “a method of pre-treatment for non-electrolysis plating of resin containing polycarbonate constituents,” and proposes a method of expanding a surface and then performing etching by removing the expanded surface. However, this method entails a somewhat complicated process and does not ensure stable properties.
Also, Korean Registered Patent No. 10-0552529 entitled “method for manufacturing of an antenna” discloses a ‘method of manufacturing an antenna for use in a wireless portable terminal that is composed of an internal antenna block manufactured from polycarbonate or a synthetic resin containing polycarbonate and an antenna loop plated on an external surface of the antenna block, where the method enables a small volume for the terminal and provides high durability.’ The specific elements of this method include etching and neutralizing the antenna block, applying polarity by pre-dipping, applying pre-treatment by activating a surface of the polarized antenna block, and forming an electroless copper plating layer on the pre-treated surface of the internal antenna block.
Also, Korean Registered Patent No. 10-0387663 entitled “method for plating engineering plastics” discloses a ‘method of’ improving plating properties for engineering plastics, with which it was previously to apply electroless plating and electroplating, by forming a primer layer by spraying and coating an ABS resin and/or a UV-curable dye over a surface of an engineering plastic, applying electroless plating or dry plating such as vacuum deposition, sputtering, ion plating, etc., coating a primer on the substrate, and then applying electroless plating.’
However, existing methods of forming an antenna pattern, by printing a pattern with ink onto a plastic surface and performing plating over the pattern, entail complicated processes and necessarily include plating processes, so that the reduced yield resulting from the plating process causes lower productivity. Moreover, plating processes are detrimental to the environment in most cases, and hence entail problems of polluting the environment and imposing health risks for workers participating in the processes.